Combined fluid pressure and mechanical bearing for gas turbine engines



Dec. 30, 1952 P. GERARD 2,623,353

COMBINED FLUID PRESSURE AND MECHANICAL BEARING FOR GAS TURBINE ENGINES Filed July 8, 1950 3 Sheets-Sheet l www 53 Dec. 30, 1952 P GERARD 2,623,353

COMBINED F D PRESSURE AND MECH AL BEARIN OR GAS TURBINE ENGINE Filed July 8, 1950 3 Sheets-5h96?. 2

\ IN V EN TOR.

Dec. 30, 1952 P. GERARD `coMRINED FLUID PRESSURE AND MECHANICAL BEARING FoR GAS TURBINE ENGINES 3 Sheets-Sheet 3 Filed July 8, 1950 W S w DVD n ,D B. D w1 m, N u m,

md B I 2mm m, @o 11|! needle bearinganda ficid bearing,

)Patented Dec. 30, 1952 UNITED STATES PATENT omer.

CQMBUEED YFLUID PRESSURE ANRME.: o ANioAL BEARING Fon GAS TURBINE NGINES Pal Grardflars, France Appicaticnljl'y 8,1950,- saisine-172,665 In France February 1, 1950 12 Claims". 1

In the patent application Sex". No. 699,(l51 of September 24, 1946, now abandoned, and inthe patent application Ser. No 172,666, led July` 8, 1950 (in the latter case jointly With HenrijS'eranne),- I have described bearings for' supporting or guiding a rotary element iri w'liiclia pressure fluid is fed between the surface of the bearing element and said rotary element and spreads" to maintain an annular clearance between said elements thereby holding the rotary element i'n a iloating state.

The feedingiiuid must be supplied under a dertain pressure, which requires afeeding source and ducts adapted to feeol the ilui'd` betweens'aidele ments. It may happen that a feeding E- com'es faulty for any i'easoii suoli as a failie of the feeding source, a break ofthe feedins'ductsor even due to the very nature of the fedingso'urce. In particular, in certain cases, the bearing ay be fed With a pressure fluid by Ineaiisofa p y p or compresser` actuated by' the' very' shaft which is journalled said bearing,

My invention has' `foi' its plii'pse, t'o iiiit the use of iluid bearings even in' the-aboife-iiiefitioiied cases, While ensuring, in particular, the' starting, i'. e. a rotation with` a suiiciently reduced friction between therotaiy eleriieit ad the bearing, evii at speeds at which the pressure flidfeeding' is' not sufci'eiit to ensure the oatiiig of Said rtaiy nement and, more' generally, a rotation of tue rotary element at ayspd vltl'l a friction sucientiy reduced to avoidar'iy risliin trie case of? an uile'xpectdf'alu of the piess'u fluid feeding" syst-ein. I

The' main object of myiiivifito is t6 provide' a bearing comp-rising, iu como riatomaiecnarncai bearing of any me,suchas'aii-oil-fnm, ball, roller I Y e. g. of the type described inthe above-mentioned patent applications, these two bearings being co-axial and one` of them being jornalled in the other one.

It Willbe understood that in a bearing" accord` ing'to the invention, independently ofthe iloati-ng action more or less' ensured" by theilui'd'lbearing during certain stages of' the` operation, the fluid` circulation ensures` the cooling. ofthe housing of the mechanical bearing` which is in contact with said iiuid.

Another object of my invention Y is' to provide a combined' bearing of they type described iti-Which urerotary eiernentlis mounted inor'on a mechant cai bearing the usual manner; the outer or inner periphery-of 'said mechanical bearing being. in turn. mounted in r'especuvelycu a cylindrical member constituting4 cneof tnfeeiments offa' uid bearing,` the chambers and grooves ofY sai'd iiuidy bearing being formed either in the outer respectively inner Wall" off therl mechanical' bearing, or

inthe inner'res'peotively'outer' Wall of=- the support? ing cylindrical member;

It is to be understood that the invention is in no way limited either to any specic type of the bearing which has been called herebefoiemef chanical bearing, this term being intended to cover all existing or' future bearings and, in particuiar, anyoil-nim, bali, roller' or needle bearing, etc. or to any sp'e ic embodiment of the iluid bearing which may be of any type and, in particular, of the type described in the above-mentioiied patent applications, or of any other existing or future typ'e, the main object of the invention being to provide a bearing constituted in combination by a mechanical bearing and by a :fluid bearing, one of said bea-rings supporting` the other one.

Another object of the invention is to provide a combination of' a mechanical bearing,- such as a ball, roller or needle bearing with a uid bearing' and, more particularly, with an air bearing and still more pa" icul'arlywith an air-bearing of the type described the above-mentioned patent applications.

A further object of the invention is to provide a device comprising in combination a gas turbine, at least tivo combined bearings according to the invention supporting the rotor of said turbine and means to feedthe air bearings of said combined bearings with compressed air supplied by the compressor driven by said turbine and particularly the compressor feeding the combustion chamber or` chambers of the turbineproper.

A 4Well-known problem in gas turbines; is to reach considerable rotation speeds and the limitation of said speeds is due, in particular, to the nature of the mechanical bearings heretoiore used.v

The-mere fact of completing the mechanical bear-l ing by a compressed air bearing surrounding said mechanical bearing orsurrounded by the same permits it to reach far higher speeds Without any risk resulting from a failure of the'airbearing and Without impairing the turbine startingand deceleration when stopping. Moreover, such a com bination implies no mechanical complication due= to thevery fact that the bearings are fedfrom the compressor driven bythe turbine, which come pressor, above a certain speed and, in' fact, iin--A mediately after starting, supplies compressedair" at pressures exceeding materially the Value re;

quired for feeding the air bearings. With com-" bined bearings according to` the invention, it is thus sufcient, for ensuring the'oating of the'- sha-ft to providea safe feeding of the compressor air into said bearings, the air consumptionbeing infact practically negligible with respectrto the normal output ot the compressor.

It Willi 1 be easily understood that the-costr of` the combined bearing with respectI toy thecost of the mechanicalnbearing alone may also beiconstoere@ as negligible.: in a' `gas turbine. Il," must' be Well understood that inA thefollowingA description" and in the claims, the eipression gas tur# 3 bine includes turbine of all known or future types, such as turbine driving an air screw, turbojets, turbines for driving cars, etc.

The operation of the bearing according to the invention, in the case of a gas turbine, is as follows:

When starting, the shaft rotates in the mechanical bearings, which implies no drawback due to the very fact of the reduced speed of said shaft during this stage. As soon as the output of the compressor reaches a sufficient pressure, the air bearings ybecome automatically operative while the mechanical bearings are made practically inoperative. In the case of an unexpected failure of the air bearings, the shaft is further supported by the mechanical bearings, which absolutely suppresses any risk. In the case of a failure of the air bearings, e. g. due to a lack of feeding pressure, the power transformed into friction which causes a wear of the parts in contact with one another is only ythe rotational kinetic energy of the part interposed between both bearings and not the rotational kinetic energy of the rotor.

The invention will be more easily understood with reference to the accompanying drawings in which, as a mere illustration, are shown some embodiments of the invention.

In these drawings:

Fig. 1 is an axial section along axis i-I of Fig. 2 of the end of a shaft journal led in a combined bearing according to the invention.

Fig. 2 is a section along axis 2-2 of Fig. l.

Fig. 3 is an axial section along axis 3-3 of Fig. 4 showing another embodiment.

Fig. 4 is a section along axis i--l of Fig. 3.

Fig. 5 shows a gas turbine designed according to the invention.

'Fig 6 is an axial sectional View on a larger scale of the bearing shown in Fig. 5 and Fig. 7 is a section along axis 'I'-'-'I of Fig. 6.

Referring first to Fig. l, there is shown at I a shaft journalled in a combined bearing according to the invention. On shaft I are screwed by means of a nut 2 two inner races 3 of ball bearings, the outer races 4 of which are secured in a sleeve 5. Sleeve 5 is journalled in turn in a iiuid bearing constituted by a body 6 provided with a cylindrical bore containing brasses Il IS--Iily described in detail hereafter, a pressure fluid being fed between the wall of said cylindrical bore and the outer wall of said brasses into the annularchamber 'l provided therebetween. A cylindrical filter' t is provided between the peripherical zone 9 and the central zone I0 of said chamber, filter 8 being soldered as shown at II on the elements in which is formed said zone 9, as described hereafter. Shaft I, both races of ball bearings 3 4, sleeve and the bore of the body 6 are all co-axial, at least when the fluidbearing operates under normal pressure. The pressure fluid is fed through a suitable duct, screwed at l2 on an inlet port provided in the upper portion of the body 5.

Referring now to Fig. 2, there is shown at IS throttlings bringing the fluid from the annular chamber 'I into the various feeding zones I3 (five in the example shown). Between the successive adjacent zones I3 are provided pressure uid outlet grooves I4 communicating with an outlet port I5 provided for this purpose at the lower portion of body 6. The above-mentioned chambers, feeding zones, throttlings and outlet grooves, are formed in the example shown, in three elements, Viz. la central ring I1 in which zones I3 and throttlings I6 are provided and two collars I8 and I9 disposed on either side of said ring I'I,

the grooves I4 being provided in ring I'i and f collar I8. Moreover zones 9 and I@ of chamber 'I' are provided between suitable shoulderings formed for this purpose on ring I1 and collar I9.

The embodiment shown in Figs. l and 2 is parfluid bearings and, in particular, to compressed air bearings, ball bearings 3- are substituted by a single central bearing having two ball rows mounted in a knee-joint. The inner race of said .bearing is shown at 3 and its knee-joint outer race is shown at 4.

In this embodiment, a pressure-tight joint 2i) of any type, adapted to ensure the tightness of the inner chamber 2l which may be, for example filled with oil, is provided between the end journal of shaft I rotatively mounted in race 3 and shaft I proper. The outer race d of the ball bearing is rotatively mounted as previously in a sleeve 5 which is journalled in turn in a gaseous iiuid bearing such as an air bearing. In this embodiment, the above-mentioned I'I-I and I9 are substituted by a one-piece sleeve II in which are provided recesses constituting the annular chamber 'I which comprises two annular compartments 9 and I6 separated from one another by a filter 8. In this embodiment, the above-mentioned feeding Zones are constituted by nozzles I3 feeding groove networks.

Referring now to Fig. 5, there is shown a gas turbine the rotor of which is journalled in combined bearings according to the invention. in

this figure, there is shown at 22 the gas turball-bearing and the rotor shaft. Both bearings of the shaft I are the same, the right hand bearing being shown in a front elevational view and the left-hand bearing being shown in an axial sectional view. 1n this gure, the parts corresponding to those of the preceding figures are designated by the same reference numbers.

Shaft 23 of the compressor carries, as shown at 24, a series of rotating bladings between which are interposed stationary bladings 25 solid with casing 22. At its other end, shaft 23 carries the blade-Wheel 26 of the turbine. The combustion chambers are shown at 21 and the fuel injectors at 28.

The operation of the device is as follows: the air is admitted at 32, compressed by bladings 24 and 25 and brought, as shown at 29, into the space located between the compression chamber and the combustion chambers. At this level are provided, on the wall of the hollow shaftv 23,A a set of holes 30 through which the compressed air penetrates into said hollow shaft. Thence, the air is projected through nozzles I3 to be interposed between the end journalsof shaft 23 and sleeves 2 integral with the inner races of the ball bearings, this assembly thus` constituting a combined bearing according to the invention. With this arrangement, during the starting stage when the air is not yet suiciently compressed so that the fluid bearing cannot support shaft 23, said shaft is supported by ball elements f bearings Bes-4. As soon as the `air pressure is sufiiciently high, the fluid bearings beccme'oi erative and support in turn shaft 23 which suppresses, in fact, any friction between the shaft and its bearings.

Figs. 6 and 7 showin detail the construction of the combined bearings used in the embodiment of Fig. 5 for supporting the rotor shaft 0f a-gas turbine. In this ligure. itinay be seen that the feeding Azones of the huid bearing lportion of the combined bearings are constituted by oil grooves 3|' arranged along 'the diagonale ofsaid feeding zones and fed substantially at their centre by theabove-'m'entioned nozzles I3. The fluid'outlet grooves are 'shown at I4. f

It is t'o be understood that the embodiment of the `gas turbine 'shown in Figs. 5 to 7 is given as a mere illustration and that any desired r'nodifica-` tion may be made thereto Awithin the scope of the invention. In particular. according to another feature of the invention, it is possible to journal in combined bearings not only the turbine rotor, as shown in Figs. `5 to 7, but also any rotating part of the'gas turbine, and more .par` ticularly the wheels carrying the directing iiuids of the compressor and/or turbine in the 'case when said wheels, instead of being integral with casing 22, are made movable for well defined purposes, as described in British Patent -No. 587,528, accepted April 29, 1947, filed by lP'v'ver Jets Ltd. Moreover, it is `obvious that it is possible to use in agas turbine instead 'of the bearings shown in Figs. 5 to' 7 combined bearings of the type shown in Figs. 3 and 4 in 'which the fiid bearing surrounds the mechanical bearing.

What is claimed is:

l1. A device for supporting a rotatable element by a stationary concentric element, comprising between said elements a mechanical antifriction bearing fast with one of said elements and mounted with a clearance with respect to the other, means to continuously freed pressure -fluid into said clearance through 'a plurality of cir-'- cumferentially spaced inlets and means to evacuate said fluid, whereby a fluid nlm is maintained between the surfaces defining said clearance, the friction between said surfaces being lower than the .friction between the elements' constituting said mechanical vantifriction bearing', whereby, when the rotatablel element is driven,- the same rotates in respect to the stationary element withoutA substantial rotation of the mechanical bearing elements in respect to each other as long as said fluid circulation is maintained at a rate sufficient to ensure the presence of said nlm.

2. In a fluid pressure bearing structure for supporting a rotatable element by a stationary element with a clearance space therebetween, the combination with a bearing surface comprising a plurality of 'circumferentially spaced 'fluid pressure zones, of at least one antifriction bearing in series with said bearing surface and including inner and louter race members and rolling'bodies therebetween, one of said race members beingin contact with one of saidelements and the-other spaced from contact with said bearing surface, whereby said antifriction bearing will automatically provide antifriction support for said rotatable element when the -rluid pressure support ceases.

3. A device for supporting a rotatable element by a stationary concentric element, comprising between said elementsa bearing device including inner and outer race members and rolling bodies therebetween, one of said race members being fast with one of said elements `and the other member being mounted with a clearance with respect to the other element, a plurality oflcir cumferentially spaced pressure zones formed in one of the surfaces defining" said clearance, means including nozzles for separately conductirigfluid under pressure to said zones; and outlet char-'rnels between said zones through which isaidf-fluid is discharged from said clearance, whereby the surfaces defining said clearance are held oiit'o'f contact with one another as long as said elevarx ance is fed with said pressure fluid. o

4. `A device for supporting a rotatable element by a stationary concentric element, comprising between said elements a bearing device including inner and outer race members 'and rolling bodies therebetween, one of 4said race members bei-ng fast with one of said elements and 'the other member being mounted with a clearance with respect to the other element, a plurality of cir# cumferentially spaced pressure zones formed f in one of the surfaces defining said clearance,A means including nozzles for separately feeding with huid under pressure each of said Zones, a system of grooves of small cross-section in each of said zones to spread said pressure fluid along the-surfaces o'f said Zones and outlet channels separating said zones through which said fluid is dise charged from said clearance,`whereby the sur# faces dening said clearance are held out of corrtact with oneanother as long as said clearance is fed with said pressure fluid.

5. A device forju'pporting a rotatableelement by a stationary concentric element, comprising between said elements a bearing-device'including inner and outer race members and rolling bodies' therebetween, one of said race members being fastwith one of said elements and the other member being mounted with a clearance with respect to the other element, a plurality of `cir cumferentially spaced pressurezones Iforz'ned in one of the surfaces defining said clearance, means including vnozzles for separately feedingI `with a compressed gas each of saidzones, a system of grooves of small cross-section in each of said cones to spread said compressed gas along'the surfaces of said zones-ausbilder ehanneisseparating said zones through whichsaid gas is dise charged from. said clearancel whereby the surfaces defining 'said clearance are held out of corri tact with one another as longas said clearance is fed withsaid compressed gas.

6. A device for supporting a rotatable element by a stationary concentric element, comprising between said elements albearing device including inner and outer race members and rolling bodies therebetween, the outer race member being fast with said stationary element and the inner race member being mounted with a clearance with respect to said rotatable element, a plurallity of circumferentially spaced pressure zones formed in one of the surfaces defining said clearance, means including nozzles for separately feeding each of said zones with a compressed gas, a sys;` tem of grooves of Smau crosssection in each ofsaid zones to spread said compressed gas along the surfaces of said zones and outlet channels separating said zones through which said gas is discharged from said clearance, 'whereby the surfaces denning said clearance are held'out of con-` tact withone another as long as said clearance is 'fed with said compressed gas.

7. A `device for supporting a rotatable element by a stationary concentric element, comprising between said elements a bearing device including inner and outer race members and rolling bodies therebetween, the inner race member being fast with sai-d rotatable element and 'the outer race member being mounted with a clearance with respect to said stationary element, a plurality of circumferentially spaced pressure zones formed in one of the surfaces defining said clearance, means including nozzles for separately feeding each of said zones with a compressed gas, a system of grooves of small cross-section in each of said zones to spread said compressed gas along the surfaces of said zones and outlet channels separating said zones through which said gas'is discharged from said clearance, whereby the surfaces deiining said clearance are held out of contact with one another as long as said clearance is fed with said compressed gas.

8. A gas turbine comprising a stationary element, a rotatable element, an air compressor driven by said rotatable element, a bearing d evice including inner and outer race members and rolling bodies therebetween, one of said race members being fast with one of said elements and the other member being mounted with` a clearance with respect to the other element, a plurality of circumferentially spaced pressure zones formed in one of the surfaces dening said clearance, means to conduct air compressed'by said air compressor into said zones, and outlet channels separating said pressure zones through which said air is discharged therefrom, whereby the surfaces defining said clearance are held out of contact with each other as long as the pressure of the air fed from said compressor is sufficient to maintain said rotatable element in a floating state.

9. A gas turbine comprising a stationary element, a rotatable element, an air compressor driven by said rotatable element, a bearing device including inner and outer race members and rolling bodies therebetween, one of said race members being fast with one of said elements and the other member being mounted with a clearance with respect to the other element, a plurality of circumferentially spaced pressure zones formed in one of the surfaces defining said clearance, means including nozzles for separately feeding each of said zones with air compressed `by said air compressona system of grooves of smallcross-section in each of said zones to spread said compressed air along the surfaces of said zones and outlet channels separating said zones through which said air is discharged from said clearance whereby the surfaces defining said clearance are held out of contact with one anr l'other as long as the pressure of the air fed from said compressor is suicient to maintain said rotatable element in a floating state.

10. Ag'as turbine comprising a stationary elee ment, a rotatable element, an air compressor driven by said rotatable element, a bearing de.- vice including inner and outer race members and rolling bodies therebetween, the inner race member being fast with said rotatable element and the outer race member being mounted with a clearance with respect to said stationary element, a plurality of circumferentially spaced pressure zones formed in one of the surfaces defining said clearance, means including nozzles for separately feeding each of said zones with air compressed by said air compressor, a system of grooves of small cross-section in each of said zones to spread said compressed air along the surfaces of said zones and outlet channels separating said zones through which said-air is discharged from said clearance whereby the surfaces defining said clearance are held out of contact with one another as long as the pressure of the air fed from said compressor is sufficient to maintain said rotatable element in a noating state.

11. A gas turbine comprising a stationary element, a rotatable element, an air compressor driven by said rotatable element, a bearing device including inner and outer race Vmembers and rolling bodies therebetween, the outer race member being fast with said stationary element and the inner race member being mounted with a clearance with respect to said rotatable element, a plurality of circumferentially spaced pressure zones formed in one of the surfaces dening said clearance, means including nozzles for separately feeding each of said zones with air compressed by said air compressona system of grooves of small cross-section in each of said zones to spread said compressed air along the surfaces of said zones and outlet channels separating said zones through which said air is discharged from said clearance whereby the surfaces defining said clearance are held out of contact with one another as long as the pressure of the air fed from said compressor is sumcient to maintain said rotatable element in a floating state.

12. A gas turbine comprising a conventional combustion system, a stationary element, a rotatable element, an air compressor driven by said rotatable element to feed compressed air to said combustion system, a bearing device including inner and outer race members and rolling bodies therebetween, one of said race members being fast with one of said elements and the other member being mounted with a clearance with respect to the other element, a plurality of circ cumferentially spaced pressure zones formed in one of the surfaces defining said clearance, means including nozzles for separately feeding each of said zones with air compressed by said air compresser, a system of grooves of small cross-section in each of said zones to spread said compressed air along the surfaces of said zones and longitudinal outlet channels separating saidY zones through which said air is discharged from said clearance whereby the surfaces defining said clearance are held out of contact with one another as long as the pressure of the air fed from said compressor is sufcient to maintain said rotatable element in a floating state.

PAUL GRARD.

REFERENCES CTED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

